A code, often referred to as a cipher, is a method used to transform information into a format that is unreadable to anyone who does not have the key or method to decode it. This technique is commonly used in communication to protect sensitive information from unauthorized access. Ciphers can be simple, like the Caesar cipher, which shifts letters in the alphabet, or more complex, involving algorithms and keys. They play a crucial role in modern cybersecurity, ensuring that data transmitted over the internet remains secure from potential threats and eavesdroppers.